import bisect

n = int(input())
a = sorted([int(input()) for _ in range(n)])
ans = 0
i = 0
while i < n:
    ans += 1
    current = a[i]
    while True:
        next_pos = bisect.bisect_right(a, current + 1)
        if next_pos >= n:
            break
        current = a[next_pos]
        i = next_pos
    i += 1
print(ans)